linux-kernel - Re: [PATCH 0/9] posix_clocks: Prepare syscalls for 64 bit time

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Message-ID: <alpine.DEB.2.20.1711170954000.1709@nanos>
Date:   Fri, 17 Nov 2017 09:58:26 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Arnd Bergmann <arnd@...db.de>
cc:     Deepa Dinamani <deepa.kernel@...il.com>,
        John Stultz <john.stultz@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
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Subject: Re: [PATCH 0/9] posix_clocks: Prepare syscalls for 64 bit time_t
 conversion

On Fri, 17 Nov 2017, Arnd Bergmann wrote:
> On Thu, Nov 16, 2017 at 10:04 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> > On Wed, 15 Nov 2017, Deepa Dinamani wrote:
> >> Would this work for everyone?
> >
> > Having extra config switches which are selectable by architectures and
> > removed when everything is converted is definitely the right way to go.
> >
> > That allows you to gradually convert stuff w/o inflicting wreckage all over
> > the place.
> 
> The CONFIG_64BIT_TIME would do that nicely for the new stuff like
> the conditional definition of __kernel_timespec, this one would get
> removed after we convert all architectures.
> 
> A second issue is how to control the compilation of the compat syscalls.
> CONFIG_COMPAT_32BIT_TIME handles that and could be defined
> in Kconfig as 'def_bool (!64BIT && CONFIG_64BIT_TIME) || COMPAT',
> this is then just a more readable way of expressing exactly when the
> functions should be built.
> 
> For completeness, there may be a third category, depending on how
> we handle things like sys_nanosleep(): Here, we want the native
> sys_nanosleep on 64-bit architectures, and compat_sys_nanosleep()
> to handle the 32-bit time_t variant on both 32-bit and 64-bit targets,
> but our plan is to not have a native 32-bit sys_nanosleep on 32-bit
> architectures any more, as new glibc should call clock_nanosleep()
> with a new syscall number instead. Should we then enclose

Isn't that going to break existing userspace?

Thanks

	tglx